Door construction



March 9, 1965 R. L. DUGGER 3,172,509

DOOR CONSTRUCTION Filed May 20, 1963 5 Sheets-Sheet 1 FIG. I

FIG. 3

INVENTOR.

BY kw fivuudclwk March 1965 R. L. DUGGER 3,172,509

DOOR CONSTRUCTION FIG. 2

INVENTOR March 9, 1965 Filed May 20 1965 R. L. DUGGER DOOR CONSTRUCTION 5 Sheets-Sheet 3 INVENTOR 544/ L- DflGEE March 9, 1965 R. DUGGER 3,172,509

DOOR CONSTRUCTION Filed May 20, 1963 Sheets-Sheet 4 V I a l ,e/czm A. 004 52 March 9, 19 65 R. 1.. DUGGER 7 DOOR CONSTRUCTION Filed May 20, 1963 5 Sheets-Sheet 5 INVENTOR.

Q fimmddo k Jo wmm 8r United States Patent 3,172,569 DOGR CONSTRUCTIGN Ralph L. Dagger, Rte. 1, Box 121, Hopkins, Minn. Filed May 20, 1963, Ser. No. 281,574 12 Claims. {C 189-46) This invention relates to an improved door construction, and more particularly to a door panel for use in large overhead doors of the type shown in my Patent 2,937,415 and co-pending application Serial No. 77,331, filed December 21, 1960. In each of the aforesaid patent and application, the door panel is an integral planar unit having a rectangular dimension sufficient to close the door opening, when the door is in its vertical position. When the door is open it is held in a flat or nearly flat condition in an elevated position in the door opening, with the upper portion of the door panel retracted back into the building and the lower portion of the door panel projecting outwardly from the building side wall.

A door panel suitable for use in the aforesaid types of doors is described in my patent and application mentioned above. The present invention is concerned with another form of door panel suitable for use in doors of the aforesaid type and is also useful generally in building construction for walls, floors, ceilings, etc.

It is an object of the present invention to provide an improved door panel construction suitable for use in large overhead doors.

It is another object of the invention to provide an im proved door panel construction having adequate strength without bending along the horizontal axis anywhere through the panel, and adequate strength against bending about the vertical axis anywhere through the panel.

It is another object of the invention to provide an improved door panel construction which may be manufactured in the factory and shipped knocked-down and assembled on the site by merely bolting the parts together.

It is another object of the invent-ion to provide an improved door panel construction which is thin and yet is strong and resists bending about the horizontal or vertical axes in the door when the door is erect.

It is a further object of the invention to provide an improved door panel construction which is weather proof, resistant to deterioration and decay, that has adequate strength to sustain stresses induced by wind blows, and to sustain loads due to moving andhandling the door during opening and closing, a door which is light in weight and yet strong, a door which can be assembled on the site from factory produced components, without use of extraordinary or expensive tools and a door which can readily be shipped.

Other and further objects are those inherent in the invention herein illustrated, described, and claimed, and will become apparent as the description proceeds.

To the accomplishment of the foregoing and related ends, this invention then comprises features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however of but a few of the various ways in which the principles of the invention may be employed.

The invention is illustrated by reference to the drawings wherein:

FIGURE 1 is a front elevational-view of an illustrative embodiment of a door constructed in accordance with the present invention;

FIGURE 2 is a sectional'view through a building having a door embodying the present invention, the sectional view being taken along the line and in the direction of arrows 2-2 of-FIGURE 1;

FIGURE 3 is an enlarged fragmentary sectional view 3,172,569 Patented Mar. 9, 1965 "ice through the head of the door shown in FIGURES 1 and URE 4;

FIGURE 6 is a much enlarged vertical sectional view corresponding to that shown in FIGURE 2. This view illustrates the door in section as held by its rigging and vertical or closed position. FIGURE 6 also shows a slight modification of the rigging as compared to FIG- URE 2;

FIGURE 7 is an enlarged fragmentary isometric view of a portion of the rear of the door in the area of arrows 7-7 of FIGURE 6, illustrating the manner in which the side rollers of the door, where used, are attached to the door;

FIGURE 8 is a separated isometric view of vertical transverse strengthening components of the door, prior to assembly. In FIGURE 8 these components are shown in the position that they are located when the observer is on the outside of the door, it being understood that the door sheeting component of the doorv is not illustrated in FIGURE 8;

FIGURE '9 is likewise a separated view of the same two components illustrated at FIGURE 8, shown withthe sheeting component of the door. In FIGURE 8 the parts are separated from each other as prior to assembly, and the components are shown as though the observer: were on the inside of the door;

FIGURE 10 is an enlarged fragmentary front'eleva-- tional view of the portion of the door at the cable attachment, this being the portion shown in the direction of arrows 1010 of FIGURE 6;

FIGURE 11 is an enlarged fragmentary horizontal view taken in the direction of arrows l111 of FIGURES 6 and 10 illustrating the same portion of the apparatus asshown in FIGURE 10, but in another direction;

FIGURE 12 is a fragmentary enlarged vertical sectional view taken in the direction of arrows 1212 of- FIGURE 11 showing the manner in which the cable ishitched to thedoor at the attachment as shown in FIG.- URES 10 and 11.

FIGURE 13 issimilar to FIGURE 8 and is a separated isometric view of the vertical transverse strengthening components of the door prior to assembly. In FIGURE 13 these components are made of wider and [thinner stock than as shown in FIGURE 8;

FIGURES 14 and 15 are related and illustrate a slight-i 1y modified form of corrugation pattern of the sheeting with corresponding modifications of the vertical trans: verse strengthening components. FIGURE 14 corresponds to FIGURES 8 and 13 and is a separated isometric view of the vertical strengthening components. FIGURE 15 is a vertical sectional view of the components shown in FIGURE 13 assembled with the sheeting between them;

Throughout the drawings the same numerals refer to the same parts.

Referring to FIGURE 1 a building B is provided with a door opening 0 which has an upper edge It a left sidejamb 11 and-a right jamb 12, as viewed from the outside of the door. The lower edge of the door opening is at floor level F. The door may be of any desired width or height. As indicated by my patent and application above mentioned, the doors of the present invention are especially suited for aircraft hangars and the embodiment of the door panel herein illustrated will be described as an aircraft hangar door of the type illustrated in my patent and application aforesaid, it being understood however that the door panel construction covered by the present invention may be used for any type of door where a flat panel is utilized or as a building component such as a wall, roof, etc., if desired. The panel has special utility for aircraft hangar doors and similar large doors.

Referring to FIGURE 2, the building generally designated B can have any kind of a roof such as a flat roof R, supported on joist J. Over the door there is provided a door truss T (FIGURE 2) of any suitable design, or if desired the building may be constructed of cantilever design, in which case the door opening is defined by the termination of transverse framing of the building, the framing being elsewhere supported in the building. In any event, however, the door opening is de fined and, as here illustrated is composed of a truss T. The truss has a mailer N at the bottom on which the sheeting S is applied to cover the truss. The lower edge of the sheeting actually defines the top of the door openmg.

The door opening is closed by one fiat door panel generally designated D. Except for side clearances SC top clearance TC and bottom clearance BC the door D entirely fills the door opening. In its vertical or closed position the door thus fills the door opening as shown in FIGURES 1 and 2 but it may be opened by raising it to the elevated. position shown in dotted lines in FIGURE 2. The door panel D always remains in a fiat, integral, planar condition. For purposes of nomenclature, the dimension W is considered as the longitudinal dimension of the panel D and the height H is considered as the transverse dimension of said panel. Also for purposes of nomenclature the side of the panel (door) which faces the outside is arbitrarily called the front side and the other side is called the reverse side. It will, of course, be understood that such nomenclature is purely arbitrary since, if the panel should be used as a floor or deck, the front side might be used as the top or the bottom.

Referring especially to FIGURES 3 through 9, the door is composed of a plurality of deeply corrugated panels or sheets generally designated 10. As shown in FIGURE 9 each sheet, according to usually available patterns will present three corrugations frontally facing 101, 10-2, 10-3 (see FIGURE 9) and a half corrugation providing the under lap 10' at the upper edge of the sheet and a half corrugation presenting the overlap 10" at the lower edge of the sheet. The height H of the corrugation is the back to front dimension, as shown in FIGURE 9 and the width of the corrugation (both at the top and the bottom) is the dimension K, as also shown in FIGURE 9. Dimensions'K and K (top and bottom) need not be identical in the present invention, because if they are different it is only necessary that other parts be dimensioned accordingly. The angularity of the corrugation viz. angle A may a so be varied. However, a stock. size angularity of corrugation is preferably used according to the present invention so as to avoid special-order rolling.

Such corrugated sheets are available in the steel trade and, pursuant this invention, standard available corrugated sheets are utilized in the door panel construction. The sheets may be either painted or galvanized or both. in the drawings, the thickness of the metal used, in the corrugated sheeting is very much exaggerated. In actual practice the corrugated sheeting is of gauge dimension. Thus 20 ga. to 24 ga. or other gauges may be customarily used. A door' constfuoted of 22 ga. galvanized sheet is stfong enough for most uses.

According to this invention the dimension H of the corrugation is utilized as the height dimension of what is essentially, a two part bar-joist construction, as follows. A bar-joist is prepared composed of the two pieces as shown in FIGURE 8. Thus one piece ZO may be a strip or T, channel or bar of any usual rolled-steel section, preferably a fiat hot rolled strip since this is cheap and adequate. Then there is prep r d a gbent piece 21, which corresponds to the zig-zag bent bar of a bar-joist, except that here, this piece 21 is preferably made as wide as piece 29 (and also piece 30, to be described). The zig-zag piece has fiat portions 21A, 21A", 21A"', etc., parallel to the strip 20 and integral angularly out-reaching portions 21B, 21B, 218', etc. integral, flat portions 21C, 21C, 210', etc. which connect the angularly out-reaching portions. The pattern is repeated throughout the full height necessary for making a zig-zag banjoist bridging element of a height sufficient to accommodate the full height of the panel P, to fit the door under construction. For purposes of nomenclature, this height-of-door dimension is called the transverse dimension, since it is transverse in respect to the corrugated sheets, which extend from side-to-side in the door.

This zig-zag strip 21 is preferably one integral strip, but may be made of separate bent pieces welded together. Strip 21 is fastened permanently to the strip 20 either by welding along the edges as at 24 or by spot welding the two together, depending on the thickness of these pieces 20 and 21 and the equipment available.

The dimension K-l-C of FIGURE 8 between the adjacent or approximate faces of the portions 21B and 21B and between 21B" and 218', etc., is made slightly greater than the dimension K of the corrugated sheet being used. See FIGURE 9. Likewise the dimension K-D is made slightly less than the dimension K of the sheeting. The dimensions C and D can be small but do provide a little clearance. The dimension H of the zig zag strip 21, reaching from the face of portions 21A, 21A, 21A, etc., FIGURE 8, to the faces of portions 21C, 21C, 21C, etc. is preferably made very slightly greater than the inside dimension H of the corrugation. Hence as the corrugated sheet S is later on pulled down, there will be clearance between the sheet S and the zigzag strip and the portions of the sheet bearing against portions 21C, 21C, 21C", etc., will be tensioned around these portions.

It will be noted from FIGURE 8 that apertures are provided in the portions 21A, 21A, 21A", etc., of the zig-zag strip and also in portions 21C, 21C, 210", etc., of the same strip. Two apertures are illustrated at each location but more can be used if the strip is wider as in FIGURES 13 and 14. Note also that the apertures at 25 are staggered, one higher and one lower, this is to avoid the lap of the sheeting S which occurs here.

The member 30 of the bar joist, which parallels member 30, is likewise composed of any convenient shape of structural steel. In this instance, because the panel is used for a door construction which is rigged and hung as described in my patent and application aforementioned, I prefer that this member 30 of the bar-joist be a T-shape, as generally designated at 30in FIGURE 8, although it could as easily be merely a flat strip. This bar-joist member 30 is likewise provided with apertures 23 matching those of the portions 21C, 21C, etc. of the zig-zag strip assembly 29-21.

Since the panel here being described is illustrated as a panel for an overhead door, there is provided means for attaching the panel to the door rigging, and for this purpose at the upper rear face of the flat bar 21 there are welded-on a pair of spaced members 26-26 which extend upwardly beyond the upper end of the fiat bar 20, and are provided with aligned apertures at 2 7 for receiving pivot pin as Will be described.

Likewise, since the panel is illustrated as a door panel of spaced ears 29-29 which are apertures to receive a clevis pin 64 for attaching suspension cables which are part of the door rigging.

With these parts one is then ready to assemble the panel, and where this panel is used for a door as here described this may be done as follows:

The door rigging may be of any of the plans illustrated in my patent and application aforementioned, and is here illustrated as consisting of a plurality of tracks 32 suitably supported at their front ends by suspensions 33 and at the rear ends 34 by hooks reaching down from the building structure. The tracks 32 each contain a roller hanger 35 having a pendant 36. The supports 33 serve also pivotally to support a pulley 3d at pivot 38. As many tracks and cables but not less than two of each, are used for supporting the door. It is not essential that the number of cables be the same as the number of tracks. The cables pass upwardly over the pulleys 39, and thence pass over guide pulleys 41 and thence run over a drum 42 downwardly toa counterweight 44. A manual drive consisting of a lower sprocket 46, hand crank 47, chain belt 48 and upper sprocket 49 on the drum shaft 59 serves adequately as a power input for rotating the drum 42 for pulling in or letting out the cables.

In assembling the door there are utilized as many of the bar-joist assemblies 20-21 as there are tracks in the particular door system being assembled. In this illustration the bar-joist assemblies 20-21 are used on the reverse side (inside) of the door and member 30 is on the outside. This is done because of appearance, and also because, where galvanized sheeting S is used and member 30 is on the outside, the member 3d can also be galvanized and since it weighs less than the assembly 29-21 the galvanizing cost is less. The assembly 26-21 need only be painted since it is protected from the weather. However from the structural standpoint, the assemblies 28-21 could be on the front side and 3% on the inside. Each of the bar-joist assemblies 20-21 is suspended from a pendant 36 of a roller hanger by means of a pivot pin 52, which is passed through the hole 27 in the upper ends of the spaced bars 26 attached to the member 20, see FIGURES 2, 3, 8 and 9. The assembly 20-21 is thus suspended and hangs vertically below the track. The lower end of each assembly is temporarily fastened in place for convenience and for holding it flush.

A lower sheet, such as sheet 10G (FIGURE 2) of the sheeting 10, is then placed onto the members 29-21, with the zigzag portions reaching into the. corrugations, as shown in FIGURE 3. With the corrugated sheet metal thus in place, and held temporarily by clamps, bolts -55 are placed in the already drilled holes in the portions 21A-21A', etc. of the assembly 2tP-21. Preferably a rectangular, flanged-edge ciip 55A having apertures in it spaced to receive the bolt 55, but of slightly heavier metal than the metal forming the corrugated sheet 10, may be placed in the corrugations before the bolts 55 are drawn down. The clips 55A can be galvanized and assist in making a tight fastening of the sheets to assemblies 20-21 at this point. When the bolts 55 are tightened it pulls the corrugation into firm engagement with the forward face of the portions 21C, 21C, 21C", etc. of the assembly 20-21. Since the dimension H ofthe zig-zag strip; 21' is made very slightly more than the dimension H of the corrugation, this will tend to impose a slight bending force on the front portions 10F of. the corrugations, Where they face against the portions 21C- 21C', etc. ofthe assembly 20-21, thereby snugly holding the corrugation in place.

It will be noted that the upper edge of the corrugation 10 is provided with a flange 10' which is faced outwardly in respect to the door and this flange 10' is positioned at about the middle of the dimension K, of the corrugation generally. The lower edge of the bottom corrugation of the next sheet is provided with a mating U-shaped bend, at 10" see FIGURE 9, which is so positioned that it will fit over the flange 10 when the next higher sheet of corrugated material is placed in proper relationship in respect to a next lower sheet of corrugated material. Accordingly, after the lower sheet 106, see FIGURES 2 and 6, has been placed and bolted, the next sheet MP is placed and bolted, and so on up until the full height of the door has been attained. Then the members 30 of the barjoist are applied to the outer surface of the corrugations and the bolts 5858 are placed and tightened.

This completes the assembly of the door except for edge trimming were used, and the attachment of other rigging components. Thus the cables 49, are preferably made with a simple eye going around a cable thimble 60, as shown in FIGURE 12. The eye in the cable is held in place by a squeeze type fastener 61. The total thickness of the fastener 61 and of the eye 60 is such that it can be put between the two plates 29-29, which were welded on opposite sides of the midfiange of the T-bar of which the member 3% is composed. A pivot pin 64 held in place by a cotter pin is all that is needed for completing the as sembly of the lower ends of the cable at to the front surface of the door.

According to my patent and application above mentioned, the lower portion of the door at pivot 72 (or 72), FIGURE 2, may be guided during opening movement by either a radius rod arrangement such as radius rod 7%, held on wall pivot 71 and pivoted to the doors 72, or this portion of the door may be guided by a wheel set at the side edge or" the door, as shown in FIGURE 7. In the latter, the side jam ll of the building may be provided with a channel 75, which is positioned to receive a wheel 76 rotating on a shaft 77 that is fixed to the door panel. Since the panel door is made of sheet metal, it is desirable, for fastening the wheels 76, to provide an additional stiffener plate generally designated 77 having the flanges 77A and 77B bent on a V-shaped corrugation 77C, as shown in FIGURE 7. This stiffener can be made of sheet metal which is heavier than the sheet metal of which the corrugation sheet is composed. In stiffener 77 there are set several webs 78'78 of still heavier metal which may be spot welded or riveted in place. These webs are apertured to receive shaft '79 which is restrained from endwise movement by appropriate collars79. The wheel 76 is made so as to journal on but not slide on shaft 77.

At each edge of the door panel there is provided an edge trim channel 90 of sheet metal which is held in place by sheet metal screws 9191. Where the roller '76 operating in the channel is used for guiding the side edge of the door panel this sheet channel 90, which is an edge trimming on the door, is apertured so as topermit the shaft 77 to pass therethrough. It will be noted from FIGURES 4 and 7 that the sheet metal channel 90, which forms an edge trimming for the door and engages the front and rear surfaces of the deeply corrugated sheets 15 and screws 91 are provided at each surface for holding the channel in place. By making channel 90 of somewhat heavier material it will, in addition to trimming the door, add substantially to the edge strength of the door edge. The channel d9 is set with minimum clearance with reference to the flanges of the channel 75 set on the sidejambs 11 and T2 of the door opening or with reference to the sidejambs, where channel 71 is not used. At the upper end of the channel %'is bent over along a slanting line soas to provide a top flange 90A which laysagainst the surface 1.0K (see FIGURE 5) uppermost of the deep corrugations of the sheet 14).

Where desired the door may be provided with a latching arrangement at the head of the door as described in my copending application, Serial No. 20,737, filed April 7, 1960, the latch being operated by a leverage 94 and pull rope 95. I

In the present invention, the corrugations of the sheet 10, being very similar in cross-sectional shape to the zigzag central member of a bar-joist contributes at least part of the strength attributable to the zigzag member of a bar-joist in the finally assembled panels of the present invention. The zig-zag member 21. contributes some of the support of this usual member in a bar-joist but it need not in this situation supply all such strength. Indeed, this member 21 can be made of quite thin stock, such as merely a wide strip of sheet metal and it will then, with the zig-zag formation of the sheeting itself provide the strength of this part of the bar-joist. Indeed, it is within the purview of the invention to eliminate member 21 entirely, merely using members 20 and 30, bolted across the assembly of the sheeting 10, but for this use, the sheeting must be of heavier stock. I prefer to um a separate member 21.

In FIGURE 13, the width of the bar-joist members is increased and their thickness decreased as compared, for example to the constiuction shown in FIGURE 8. Thus members 120, 121 and 130 are all made of wide strips of sheet metal such. as heavy gauge sheet metal, and as wide as needed to provide the desired sectional areas, rather than to use the corresponding thicker and narrower shapes 20, 21 and 30 of FIGURE 8 Otherwise the construction of FIGURE 13 is like FIGURE 8; Members 129 and 121 are spot welded (or otherwise secured together) in the areas 121A. Welds are shown by a scattering of x-marks designated 122, in these areas, denoting for example spot Welds. Several holes 124 are also provided in these areas, it being noted that where the laps of sheets S occur, these holes are spaced above and below the lap (not shown in FIGURE 13). Also holes are provided at 125 in portions 121C of the member 121 and matching holes 126 are provided in member 130. The supports and brackets corresponding to members 26-26 and Z9-29 of FIGURES 6, 8, 10, l1 and 12 are not shown in FIGURE 13, but it will be understood that these will be provided as needed when the panel is used as a door panel for doors of my patent and application above mentioned.

In FIGURES 14 and 15 there is illustrated the manner in which the invention is utilized when the corrugated sheeting has rounded corrugation crests. Thus members 220 and 230 are the same as members 129 and 130 or narrower and thicker stock may be used as in FIGURE 8. However, the bends 221B and 221B are made rounded. Since the corrugation bends of the sheet metal S are also rounded the welds 222 and holes 224 and 225 can be for example as in FIGURE 13.

Now, it is preferable that the bends at 22113 in member 221 be of slightly larger radius on the inside than the outside radius of the mating bends of the corrugations in sheet S and that the bends 221B in member 221 be the same or of slightly smaller radius than the inside radius of the mating bends of the corrugations in sheet S. Then, if the dimension H (from the inside surface of bend 221B to the outside surface of bend 221B of member 221 is made just slightly larger than the depth of corrugation in the sheet S when the metal is relaxed, the corrugations will rest on bends 221B and will not (until later or drawn down), seat in the inside surfaces of bends 221B. Then to assemble, some apertured fillers 256, which are flat on the corrugations of the sheet S, are put in place in place and bolts 255 are inserted and pulled tight. Fillers 256 should be of a length to reach across the width of strip 221 so as to distribute the clamping force of the bolts. This has the effect of drawing the corrugations of sheet S snugly into the bends of strip 22]..

Strip 230 is then put in place and fillers 257 (similar to fillers 256) are inserted and bolts 258 entered and pulled down tight. This completes the assembly of the panel.

It will be noted that corrugated sheets S as shown in FIGURE 15 may be fabricated so as to provide a lap at one side and curved on the other side to fit the inside of any bend 221B or 221B.

As many of the assemblies -21-30 (or 120-121-130 or 220221-230) are used at spaced intervals across the width of the panel, so as to provide necessary strength against bending of the panel around an axis parallel to the corrugations of sheet S. In this respect utilization of the invention is exceedingly flexible.

As many widely apparently different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments herein.

1. A door panel having a reverse side and a front side What is claimed is: and having longitudinal and transverse dimensions at right angles to each other and corresponding to the width and height of the door, respectively, comprising a plurality of sheets having deep V-shaped corrugations of a shape generally symmetrical about a central plane through said sheets, said corrugations extending lengthwise of said sheets, said sheets being laid in side-by-side and edgelapped relationship with the corrugations parallel to the longitudinal dimensions of the panel across the width of the door so that said panel presents front corrugation crests longitudinally on the front side of the panel and :reverse corrugation crests on the reverse side of the panel, :and a transverse stiffening assembly on the inside of the door extending across the panel paralleling the transverse dimension thereof, said stiffening assembly being com posed of an elongated member having V-shaped zig-zag bends therein extending across the panel on the reverse .side, said member being shaped so as to follow the corrugations and be in contact with rear areas of contact on successive reverse corrugation crests and generally follow the corrugations and contact the reverse side at areas of contact of front corrugation crests, and a reverse side reinforcing member extending straight across and bridging the corrugations and overlying said zig-zag bent member on the reverse side of the panel, said reverse'side reinforcing member contacting the zig-zag bent member at said rear areas of contact, fastenings extending through the reverse side reinforcing members, said zig-zag bent members and sheet at said rear areas of contact, and a front side reinforcing member parallel to said rear side reinforcing member laid on the front of the panel so as to bridge the front, said corrugation crests in front areas of contact, and fastenings through said front side reinforcing member, and sheet and said zig-zag bent member at said front side areas of contact, and a suspension attachment on one end of said reverse side reinforcing member and a suspension connection intermediate the ends of the front side reinforcing member.

2. The panel of claim 1 further characterized in that said panel contains at least two stiffening assemblies spaced parallel to each other at intervals along the panel.

3. The panel of claim 1 further characterized in that edge-to-edge laps of the corrugated sheets occur at a corrugation crest.

4. The panel of claim 1 further characterized in that the elongated member and reverse side reinforcing mernber are fiat strips.

5. The panel of claim 4 further characterized in that the elongated. member and reverse side reinforcing member are fiat strips and the front side reinforcing member has a flat portion contacting the corrugations and a flange extending outwardly therefrom.

6. The panel of claim 1 further characterized in that the elongated member and the reverse and front side reinforcing members are flat strips.

7. The panel of claim 1 further characterized in that one of said reinforcing members is extended beyond the side edge of the panel so as to'provide a mounting for receiving an attachment.

8. The panel of claim 1 further characterized in that the suspension connection intermediate the ends of said front side reinforcing member for anchoring a suspension means is located in that half of the length of said reinforcing element which is opposite to the end of the reverse side reinforcing element on which said suspension attachment is mounted.

9. The panel of claim 1 further characterized in that the side edges of the panel at which the corrugations end are covered with a smooth facing embracing the ends of the corrugations.

10. The panel of claim 1 further characterized in that a reinforcing pan is fastened in one corrugation at opposite ends thereof, said pan forming a support for a pivot axle extending beyond the ends of the corrugation, and a wheel is provided on said axle.

11. The panel of claim 1 further characterized in that a shaped washer is seated in the corrugations at the rear areas of contact and the fastenings put therethrough for distributing the attachment force over a wider area of contact and against said zig-zag bent strip.

12. The panel of claim 1 further characterized, a

shaped washer is placed against the reverse face of the zig-zag bent strip at said front areas of contact and the fastenings placed therethrough.

References Cited by the Examiner UNITED STATES PATENTS HARRISON R. MOSELEY, Primary Examiner. 

1. A DOOR PANEL HAVING A REVERSE SIDE AND A FRONT SIDE AND HAVING LONGITUDINAL AND TRANSVERSE DIMENSIONS AT RIGHT ANGLES TO EACH OTHER AND CORRESPONDING TO THE WIDTH AND HEIGHT OF THE DOOR, RESPECTIVELY, COMPRISING A PLURALITY OF SHEETS HAVING DEEP V-SHAPED CORRUGATIONS OF A SHAPE GENERALLY SYMMETRICAL ABOUT A CENTRAL PLANE THROUGH SAID SHEETS, SAID CORRUGATIONS EXTENDING LENGTHWISE OF SAID SHEETS, SAID SHEETS BEING LAID IN SIDE-BY-SIDE AND EDGELAPPER RELATIONSHIP WITH THE CORRUGATIONS PARALLEL TO THE LONGITUDINAL DIMENSIONS OF THE PANEL ACROSS THE WIDTH OD THE DOOR SO THAT SAID PANEL PRESENTS FRONT CORRUGATION CRESTS LONGITUDINALLY ON THE FRONT SIDE OF THE PANEL AND REVERSE CORRUGATION CRESTS ON THE REVERSE SIDE OF THE PANEL, AND A TRANSVERSE STIFFENING ASSEMBLY ON THE INSIDE OF THE DOOR EXTENDING ACROSS THE PANEL PARALLELING THE TRANSVERSE DIMENSION THEREOF, SAID STIFFENING ASSEMBLY BEING COMPOSED OF AN ELONGATED MEMBER HAVING U-SHAPED ZIG-ZAG BENDS THEREIN EXTENDING ACROSS THE PANEL ON THE REVERSE SIDE, SAID MEMBER BEING SHAPED SO AS TO FOLLOW THE CORRUGATIONS AND BE IN CONTACT WITH REAR AREAS OF CONTACT ON SUCCESSIVE REVERSE CORRUGATION CRESTS AND GENERALLY FOLLOW THE CORRUGATIONS AND CONTACT THE REVERSE SIDE AT AREAS OF CONTACT OF FRONT CORRUGATION CRESTS, AND A REVERSE SIDE REINFORCING MEMBER EXTENDING STRAIGHT ACROSS AND BRIDGING THE CORRUGATIONS AND OVERLYING SAID ZIG-ZAG BENT MEMBER ON THE REVERSE SIDE OF THE PANEL, SAID REVERSE SIDE REINFORCING MEMBER CONTACTING THE ZIG-ZAG BENT MEMBER AT SAID REAR AREAS OF CONTACT, FASTENINGS EXTENDING THROUGH THE REVERSE SIDE REINFORCING MEMBERS, SAID ZIG-ZAG BENT MEMBERS AND SHEET AT SAID REAR AREAS OF CONTACT, AND A FRONT SIDE REINFORCING MEMBER PARALLEL TO SAID REAR SIDE REINFORCING MEMBER LAID ON THE FRONT OF THE PANEL SO AS TO BRIDGE THE FRONT, SAID CORRUGATION CRESTS IN FRONT AREAS OF CONTACT, AND FASTENING THROUGH SAID FRONT SIDE REINFORCING MEMBER, AND SHEET AND SAID ZIG-ZAG BENT MEMBER AT SAID FRONT SIDE AREAS OF CONTACT, AND A SUSPENSION ATTACHMENT ON ONE END OF SAID REVERSE SIDE REINFORCING MEMBER AND A SUSPENSION CONNECTION INTERMEDIATE THE ENDS OF THE FRONT SIDE REINFORCING MEMBER. 